Latchable magnetic reed switch

ABSTRACT

A U-shaped bar of so-called remanent magnetic material serves as a core for actuating one or more magnetic reed switches that are mounted between the legs of the U with their magnetic axes generally parallel with the bight of the U. Two coils are positioned around the bight of the U, one wound upon an axis parallel to the bight, and the other wound on an axis orthogonal to the bight. The switch, or switches are latched selectively and alternately in either their closed or open position, depending on which of the two coils is energized. The condition of the device may be sensed magnetically in a manner similar to the reading of magnetic memory devices.

United States Patent [191 Launt [11 3,775,712 Nov. 27, 1973 LATCHABLEMAGNETIC REED SWITCH [75] ln'ventorz- Larry L. Launt, Livonia, N.Y.

[7-3] Assignce: Information Transfer, Inc.,

Holcomb, NY.

[22] Filed: Mar. 12, 1973 [21] Appl. No.: 339,718

[52 US. Cl. 335/153, 335/183 [51] Int. Cl. H0111 51/27 [58] Field ofSearch 335/151, 153, 154, 335/152, 183, 266, 267, 268

[56] References Cited UNITED STATES PATENTS 3,211,857 10/1965 Warrington335/153 X 3,217,122 11/1965 Bernstein 335/153'X 3,364,449 'l/1968 Gouldet al. 335/153 3,486,138 12/1969 Chalmers et al 335/153 X PrimaryExaminer Roy N. Envall, Jr. Attorney-Hoffman Stone [57] ABSTRACT AU-shaped bar of so-called remanent magnetic material serves as a corefor actuating one or more magnetic reed switches that are mountedbetween the legs of the U with their magnetic-axes generally parallelwith the bight of the U. Two coils are positioned around the bight ofthe U, one wound upon an axis parallel to the bight, and the other woundon an axis orthogonal to the bight. The switch, or switches are latchedselectively and alternately in either their closed or open position,depending on which of the two coils is energized. The condition of thedevice may be sensed magnetically in a manner similar to the reading ofmagnetic memory devices.

5 Claims, 5 Drawing Figures alternate opening and closing responsivelyto changes in the magnetic conditionof'the core. a r

In the patented device a pair ofcoilsare mounted at opposite respectiveendsofa straight, bar-like'core of a remanent magnetic material, andthereed switches are juxtaposedwith the core. When the coils areenergized simultaneouslyina magnetically aiding 'direction, the core ismagnetized. to act-like a single permanent magnet, the opposite ends ofthe core :being driven to opposite respective. magnetic -polarities, and"the switches are drawn and. held closed. When, however,

the coilsare energized in magnetic opposition :to, ea'ch other, the coreis magnetically-divided into two opposed magnets, 'Theendsof the coreare bothflf one polarity, andthe polesofthe otherpolarityare near thecenter'of the core. The switches are then biased and held open. i

Other, more or less similar arrangementshave also 7 been proposed, someusing a permanent magnet in place of one of Ketchledgescoils. I

The previous arrangements have been subjectto certain, disadvantages anddifficulties, especially :in respect of driving the switches from theirclosed totheir open positions. In the Ketchledge arrangementgforexample,

one musteither energizeboth coils simultaneously at closely matchedenergy .values,'or energize one of the coils to a critical'value, elsethe desiredmagneticsplitting of the core inhalf will not beachievedproperly. The present invention avoids'thisproblem, and providesa switching device of improved versatility, simplicity, reliability, andease of control. I

Briefly, a switching device according to the invention includes a coreof a remanentmagnetic material that in its basic form is U-shaped,although in actual practice preferably I-I-shape'd, resemblingtwo'U-shaped cores in a common plane with theinbightportions integrallyjoined together. Magnetic reedswitches are. mounted between the legs ofthe'U, and a'pair of mutually orthogonal coils are mounted upon the"bight ofthe U.

When the coil that is wound on anaxis parallel *to'the bight isenergized, the core is magnetized as a simple horseshoe magnet with theflux gap extending between the legs, through the reed switches, and theswitches are driven closed. When, however, the coil wound on an axisparallel to the legs of theU is energized, the

core becomes magnetized as a simple bar magnet, the

legs are of the same magnetic polarityfand a'force of repulsion isproduced between the opposed reeds'of the switches to open the switchesand hold them open.

In the ordinary case, the energizing currentsapplied to the coils toactuate'theswitches-are simply'pulses of "sufficient value anddurationto saturate the core. Their magnitude is not critical, exceptasto a minimum value,

and, so far as the magnetic actionis concerned, his not possible tooverdrive the coils. Norisitever desired to -energize both coilssimultaneously. One coil actuates the switches to one position andleaves them latched there, and the othercoil actuates the-switchesto'the opposite position, and leaves them latched there. The

operation.

arrangementis 'simplerconvenient, and non-critical in Auxillary reedswitches may be mounted alongside the legs of the cores for operation inopposite mode from the switches that extend between the legs. Thus, anoff-normal-switch may be included, or operation as adouble throw switchmay bereadily achieved.

" Finally, the-magnetic condition of the core may be readilysensed'through either-oneof the coils, or a 4 separate sen seT-winding;by'pulse interrogation methods similar to those used for readingmagnetic'memory devices, preferablyoneof the non-destructive methodsWAR/V n Representative embodiments of the invention will now bedescribed in detail in conjunction with the accomp'anying' drawing,-wherein: f I. FIGS. 1A and 1B are schematic plan views of a typicaldevice according to the invention illustrating the theory of operationon which it is based; I

FIG. 2 is a plan-view of a switching device according to a'first,representative embodiment of the invention; FIG. 3 is aside elevationalviewof the device shown in "FIG.- 2; and I.

FIG. 4 is "a plan .view of a' second, and presently preferred embodimentof the invention. As shown in FIGS. 1A and 1B, the core 10 isalternately switched betweena horseshoe condition, FIG.

--lA, and a bar condition, FIG. 1B, by alternatelyenergizing the twocoils 12 and 14 that are mounted on the bight portion 16 of the coreorthogonally to each other. Reed switches 18, normally regarded'as themain switches, are mounted between the legs 20 and 21 of and parallel tothe legs. v 1

The core '10.is preferably made of remanent magnetic material such asthe alloy known commercially as .Remadur, or certain ferritecompositions, that is capable of remaining magnetically saturated onceit .is driven to saturation by energization of one of the coils l2 and14. Several materials having the desired remanence characteristics arecommercially available and well-known. 5 g As shown in FIGS. 2 and 3, atypical switching device according to the invention may comprise a pairof H- shaped core pieces 30 and 31, each of which consists of two sheetsof Remadur alloy about 0.015 inch thick.

- The core pieces are in face to face opposition and spaced apart about0.1 inch, or just far enough to accommodate the main reed switches 34and 35 that are mounted between their leg portions 32 and 33,respectively, Inmostutilizations three switches 34 and 35 at The twocoils 12 and 14 are mounted upon the bightportion 37 of the core and areconnected to any desired control circuit for selective alternateenergization. Y

The instantaneous magnetic condition of thecore maybe ascertained byapplying an electrical pulse of relatively small amplitude to one of thecoils Hand 14, and sensing the resulting and ensuing electrical effectsin that coil or the other one, or in a separate sense tween'the opposedlegsof said core with its magnetic axis generally parallel to the bightof said core, and a pair of energizing coils mounted upon the bight ofsaid core, one of said coils having its winding axis parallel to thelength of the bight, and the other one of said c'oils havingits windingaxis orthogonal to the bight.

with each other and the condition of a particular core ascertained by.the effect on the sense windings immediately following the applicationof an interrogating pulse to the core of interest.

An alternative embodiment of the invention is shown in FIG.'4. Itincludes so-called off-normal contacts constituted by an auxilliary pairof reed switches 40 and 41 mounted alongside the core pieces 44. In thiscase, to maximize the magnetic flux applied to the off-normal contacts40 and 41, the core pieces differ from the core pieces 30 and 31 shownin FIGS. 2 and 3 in that they include integrally formed tabs 47extending laterally outwardly at the bight end of each leg. Theoff-normal contacts 40 and 41 operate oppositely from the main contacts34 and 35, being open when the main contacts are closed, and vice versa.

Switching devices of theinvention do not require reed switches ofspecial design for. the off-normal contacts. Instead, all of the reedswitches in thedevices may be of the standard type known commercially asForm A, in which the contacts are normally open, and are closed only inresponse to magnetic flux passin through them.

What is claimed is:

l. A magnetically controllable switching device comprising a U-shapedcore of a remanent magnetic material, a magnetically responsive reedswitch mounted be- 2. A switching device according to claim 1 includingan auxilliary magnetically responsive reed switch mounted alongside.ofone of the legs of said core and generally parallel .r thereto foractuation in an electrically opposite mode from said first named switch,being open when said first named switch-is closed and vice versa.

3. A switching device according to claim- 1' including an auxilliarywinding upon a selected portion of said core for sensing the magnetic.response to said core to i a current of small amplitude and shortduration passed through one of said pair of coils.

4. A magnetically controllable switching device comprising an I-l-shapedcore of'a remanent magnetic material, -a magnetically responsive reedswitch mounted betwen a selected pair of opposed legs of said core withits magnetic axis generally parallel to the cross-bar of the H, and apair of energizing coils mounted on the cross-bar portion of said core,one ,of said coils being oriented with its winding axis parallel to theleg portions of the core, and the other one of said coils having itswinding axis orthogonally thereto.

5. A switching device according to claim 4 including an auxiliaryreedswitch juxtaposed with said core laterally outwardly thereof foroperation in an electrically opposite mode from said first named switch,being open when said first named switch is closed and vice versa.

1. A magnetically controllable switching device comprising a Ushapedcore of a remanent magnetic material, a magnetically responsive reedswitch mounted between the opposed legs of said core with its magneticaxis generally parallel to the bight of said core, and a pair ofenergizing coils mounted upon the bight of said core, one of said coilshaving its winding axis parallel to the length of the bight, and theother one of said coils having its winding axis orthogonal to the bight.2. A switching device according to claim 1 including an auxilliarymagnetically responsive reed switch mounted alongside of one of the legsof said core and generally parallel thereto for actuation in anelectrically opposite mode from said first named switch, being open whensaid first named switch is closed and vice versa.
 3. A switching deviceaccording to claim 1 including an auxilliary winding upon a selectedportion of said core for sensing the magnetic response to said core to acurrent of small amplitude and short duration passed through one of saidpair of coils.
 4. A magnetically controllable switching devicecomprising an H-shaped core of a remanent magnetic material, amagnetically responsive reed switch mounted betwen a selected pair ofopposed legs of said core with its magnetic axis generally parallel tothe cross-bar of the H, and a pair of energizing coils mounted on thecross-bar portion of said core, one of said coils being oriented withits winding axis parallel to the leg portions of the core, and the otherone of said coils having its winding axis orthogonally thereto.
 5. Aswitching device according to claim 4 including an auxiliary reed switchjuxtaposed with said core laterally outwardly thereof for operation inan electrically opposite mode from said first named switch, being openwhen said first named switch is closed and vice versa.